Take a look and you'll understand it right away. It's organized with nodes and links. Nodes perform operations, and links transport data between nodes. You can arrange them visually as you please. There's even stuff like "metanodes" that allow you to put nodes inside, so you don't have to have a messy playground.
Most nodes (there are official and 3rd party nodes) do have error output, and there's a console to inspect what's going on.
You can also inspect data visually in most nodes.
Even someone who is not used to play with data, who doesn't understand consistency and yada yada will understand the advantages.
It uses a visual data flow approach to transform data step by step from one form to another. This approach is much better for data transformation. It is also less error prone as operations take place on columns or rows of data, not cells. But you wouldn't try to create a set of company accounts with it.
